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Synthesis of α‐Carbolines Starting from 2,3‐Dichloropyridines and Substituted Anilines
Author(s) -
Hostyn Steven,
Van Baelen Gitte,
Lemière Guy L. F.,
Maes Bert U. W.
Publication year - 2008
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.200800077
Subject(s) - chemistry , intramolecular force , pyridine , intermolecular force , ring (chemistry) , medicinal chemistry , organic base , base (topology) , nitrogen , catalysis , smiles rearrangement , reaction conditions , organic chemistry , molecule , mathematical analysis , mathematics
9 H ‐α‐Carbolines have been prepared via consecutive intermolecular Buchwald–Hartwig reaction and Pd‐catalyzed intramolecular direct arylation from commercially available 2,3‐dichloropyridines and substituted anilines. The combination of a high reaction temperature (180 °C) and the use of DBU were found to be crucial for the intramolecular direct arylation reactions of the 3‐chloro‐ N ‐phenylpyridin‐2‐amines as no reaction was observed at 120 °C and 180 °C using different inorganic and other organic bases. On the other hand, nitrogen‐methylated pyridine analogues of these substrates { N ‐[3‐chloro‐1‐methylpyridin‐2(1 H )‐ylidene]anilines} do undergo ring closure at 120 °C, with K 3 PO 4 as base, affording the respective 1‐methyl‐1 H ‐α‐carbolines in good yields.